Cardiovascular consequences of the inspiratory muscle metaboreflex: Effects of age and sex

Joshua R. Smith, Andrew M. Alexander, Shane M. Hammer, Kaylin D. Didier, Stephanie P. Kurti, Ryan M. Broxterman, Thomas J. Barstow, Craig A. Harms

Research output: Contribution to journalArticlepeer-review


With inspiratory muscle metaboreflex activation, we hypothesized that, compared with their younger counterparts, older men and women would exhibit greater 1 increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and 2) decreases in limb blood flow (˙L) but 3) no sex differences would be present in older adults. Sixteen young adults [8 young men (YM) and 8 young women (YW), 18-24 yr] and 16 older adults [8 older men (OM) and 8 older women (OW), 60-73 yr] performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths/min with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, QL was determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9±8.1 mmHg) compared with YW (6.9±1.4 mmHg) but not (P<0.05) between OM (12.3±5.7 mmHg) and YM (10.8±5.7 mmHg). OW (20.2±7.2%) had ˙L greater (P< 0.05) decreases in QL compared with YW (-9.4±10.2%), but no significant differences were present between OM (22.8 9.7%) and YM (-22.7 11.3%) during the 65% IRBT. The 65% IRBT led to greater (P<0.05) increases in LVR in OW (48.2±25.5%) compared with YW (19.7±15.0%), but no differences (P<0.05) existed among OM (54.4±17.8%) and YM (47.1±23.3%). No significant differences were present in MAP, QL, or LVR between OM and OW. These data suggest that OW exhibit a greater inspiratory muscle metaboreflex compared with YW, whereas no differences between OM and YM existed. Finally, sex differences in the inspiratory muscle metaboreflex are not present in older adults. NEW & NOTEWORTHY Premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with young men; however, it is unknown whether these sex differences are present in older adults. Older women exhibited a greater inspiratory muscle metaboreflex compared with premenopausal women, whereas no differences were present between older and younger men.

Original languageEnglish (US)
Pages (from-to)H1013-H1020
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number5
StatePublished - May 2017


  • Aging
  • Blood pressure
  • Limb vascular resistance
  • Metaboreflex

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


Dive into the research topics of 'Cardiovascular consequences of the inspiratory muscle metaboreflex: Effects of age and sex'. Together they form a unique fingerprint.

Cite this